Press Trust of India
January 18, 2019 1:51 PM IST
An artificial intelligence system identified a previously unknown human ancestor that traveled the planet tens of thousands of years ago and left a genomic footprint in Asian individuals, scientists say.
By combining deep learning algorithms and statistical methods, researchers at the University of Tartu in Estonia, the Institute for Evolutionary Biology (IBE) and the Genomic Regulation Center (CRG) in Spain found that the extinct species were a hybrid of Neanderthals and denisovans and crossed with modern humans in Asia. The finding, published in Nature Communications, would explain that the hybrid found last year in the Denisova caves – the offspring of a Neanderthal mother and a Denisovan's father – was not an isolated case but part of a more general introgression process .
Researchers used deep learning for the first time to explain human evolution, opening the way for the application of this technology to other issues in biology, genomics, and evolution.
One of the ways to distinguish between two species is that, although both may intersect, they generally do not produce fertile offspring.
However, this concept is much more complex when extinct species are involved.
Indeed, the story told by current human DNA blurs the lines of these boundaries, preserving fragments of hominids from other species, such as Neanderthals and Denisovans, who coexisted with modern humans more than 40,000 years ago in Eurasia.
"About 80,000 years ago, there was the so-called Out of Africa, when part of the human population, which already consisted of modern humans, left the African continent and migrated to other continents, giving birth to all current populations," said Jaume. Bertranpetit, IBE's principal investigator.
"We know that modern humans have since crossed with the Neanderthals on all continents, except in Africa, with the Denisovans in Oceania and probably in Southeast Asia, although evidence of crossings with a third extinct species has not been confirmed with some certainty, "said Bertranpetit.
Until then, the existence of the third ancestor was only a theory that would explain the origin of some fragments of the current human genome (part of the team involved in this study had already proposed the existence of the extinct hominid in an earlier study). However, deep learning made it possible for DNA to transition to the demographics of ancestral populations.
It is the first time that deep learning is successfully used to explain human history, opening the way for this technology to be applied to other issues in biology, genomics and evolution.
The deep learning analysis revealed that the extinct hominid is probably a descendant of the Neanderthal and Denisovana populations.
"Our theory coincides with the hybrid specimen recently discovered in Denisova, although we can not yet rule out other possibilities," said Mayukh Mondal, a researcher at Tartu University.
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